Combined traveling wave and cathode ray oscilloscope tube



Sept. 7, 1965 F. L. KATZMANN 3,205,397 COMBINED TRAVELING WAVE AND CATHODE RAY OSCILLOSCOPE TUBE Filed Feb. 27, 1961 osc. I416 l +23 VIDEO SIGNAL FIG. 3

b lBc 33 INVENTOR. W FRED L. KATZMANN BY OQwJgxOQQ ATTORNEYS United States Patent 3,205 397 COMBINED TRAVELING WAVE AND CATHODE RAY OSCILLOSCOPE TUBE Fred L. Katzmann, Cedar Grove, N.J., assignor to Fairchild Camera and Instrument Corporation, Syosset,

N.Y., a corporation of Delaware Filed Feb. 27, 1961, Ser. No. 91,941 13 Claims. (Cl. 315-3) The present invention relates to cathode ray tubes and particularly to cathode ray tubes combined with travelling wave means for producing deflection of the electron beam in one dimension, the travelling wave means being enclosed within the same envelope with the usual cathode ray tube and its deflection means. By utilizing a single envelope enclosing both a source of electrons which is velocity modulated by travelling wave means and a second source of an electron beam which is deflected by the ouput of the travelling wave section it is possible to combine a low noise band-pass amplifier, wide band detector, video amplifier and electrostatic deflection system with the usual cathode ray oscilloscope tube.

In the past, travelling wave tubes have been made wherein the output of the tube intensity modulated a cathode ray beam, but no device has been manufactured or suggested which combines a travelling wave amplifier tube with an electrostatically deflected cathode ray tube to produce a complete amplifying, detecting and deflecting system such as indicated above. It will be readily appreciated that such a complete wave deflected cathode ray tube is extremely useful for the presentation of information on oscilloscopes or on A type radar screens.

It is an object of my invention to provide a combined travelling wave amplifier tube and cathode ray oscilloscope tube wherein the oscilloscope beam deflection in one dimension is caused by the output of the travelling wave amplifier tube.

It is another object of my invention to provide such a combined travelling wave amplifier, velocity sorting aperture demodulator, and electrostatically deflected cathode ray tube wherein the tube sections are in a single evacuated envelope.

It is another object of my invention to provide a combined tube wherein electron multiplication is employed.

It is a further object to provide such a combined tube using an electron multiplier structure wherein the deflection plates of the cathode ray tube are sectionalized and are connected to the multiplier dynodes successively to thereby reduce problems arising from the transit time of the electrons from dynode to dynode.

Other objects and features of the invention will be apparent when the following description is considered in connection with the annexed drawings, in which,

FIGURE 1 is a schematic view of a combined travelling wave amplifier, detector, and electrostatically deflected cathode ray tube in which the electron multiplier output is connected directly to one pair of beam deflection plates;

FIGURE 2 is a similar View of the modified form of the invention wherein the electron multiplier dynodes are connected progressively to a series of deflecting plates; and

FIGURE 3 is a fragmentary illustration of a modification of the FIGURE 2 structure.

Referring now to FIGURE 1, it will be seen that the tube of my invention comprises an envelope having the usual phosphor coated-faceplate 11, funnel portion 12 and cylindrical neck portion 13. At one end of the neck portion 13 there is mounted the usual electron gun having a cathode 14, control grid 15 and focussing and 3,Zfl5,397 Patented Sept. 7, 1965 accelerating anodes 16 and 17. Between the electron gun and screen 11 are the usual deflection plates 1818 and 19.

In addition to the cylindrical neck portion 13 there is made integrally with the tube 10 a second cylnidrical portion 20 which extends at right angles to the portion 13. The cylindrical portion 20 contains a second electron gun which is again provided with the usual cathode 21, control grid 22 and accelerating anode 23. Likewise provided in cylindrical portion 20 is a helix or helical line 24 to which a desired potential is applied.

The signal to be observed may be a modulated high frequency such as a radar signal, in which case after amplification it is applied directly to electrode 25 reactively coupled to the helical line at its lower end. If the signal to be observed is a video signal or one of lower frequency, a high frequency oscillator and modulator must be provided as shown in FIG. 1.

In a similar manner, an electrode 26 is positioned adjacent the opposite end of the helical line, reactively coupled thereto and connected to a resistor serving as a load or terminating impedance for the helical line 24 and returned to a point of suitable reference potential. Adjacent the helical line 24 at the end opposite the electron gun is a plate 27 having an aperture therein, this plate serving, as will hereinafter appear, as a velocity sorting or demodulating aperture. Between the apertured plate 27 and the horizontally extending cylindrical portion 13 of tube 10 is a series of dynodes 28, 30, 31, 32 and 33, the last dynode being arranged to direct the electrons emitted therefrom against one of the vertical deflection plates 18 of the tube 10. This plate serves as a collecting anode for the electron multiplier and is connected by means of a lead 34 to a resist-or 35 and thence to ground, the opposite plate of the pair 18 being connected to B+ through the variable resistor 39.

It will be seen that the electron beam formed by coaction of the cathode 21, grid 22 and accelerating anode 23 is directed down the axis of the helical line 24. The input signal travels down the helical line and in so doing causes bunching of the electrons, that is, causes velocity modulation of the electron beam. The apertured plate 27 is biased by placing a desired positive voltage thereon such that all electrons leaving the helical line 24 at a velocity greater than a predetermined value will emerge from the aperture at the side remote from the helical line 24, whereas electrons having a velocity less than a predetermined velocity will not pass through the aperture.

The number of electrons emerging from the aperture will thus be directly proportional to the amplitude modulation of the input signal and the electron stream pulses emerging from the aperture in plate 27 constitute the demodulated input signal. These pulses are then amplified by means of the electron multiplier dynodes 23, 30, 31, 32 and 33, the collector plate of the electron multiplier being the deflection plate of the horizontally disposed cathode ray tube as described hereinabove. The anode or collector plate 18 is terminated as indicated in the low impedance represented by resistor 35, while the other plate of the pair of deflection plates 18 is connected to B+. This latter potential is nominally at the voltage level of plate 18 and may be varied for beam positioning on the display cathode ray tube screen. It will be understood that the electron current from the final dynode 33 of the electron multiplier flows via the deflection plate 18 through resistor 35. The variation of this current through resistor 35 develops a voltage thereacross which is therefore directly related to the video information modulated on the carrier wave introduced into the system at the input electrode 25. The voltage across resistor 35 also appears at the lower deflection plate 18 and causes the cathode ray beam to be deflected proportionally to the amplified video information. Consequently, the voltage across plates 18 corresponds to the modulation on the input signal and the beam is deflected in one direction, usually the vertical direction by corresponding amounts. Of course, a sweep signal is applied to the horizontal deflection plates 19 in the usual manner to supply a time base for the display of the input signals.

Referring now to FIGURE 2, the arrangement shown therein is generally similar to that shown in FIGURE 1. However, in this case the vertical deflection plates 18 are subdivided into the pairs of plates 18a, 18b, 18c and 18d and additionally the dynodcs are arranged along an axis generally parallel to the beam axis of the display cathode ray tube and are connected individually to the successive deflection plates. In this manner the progressively higher voltage present on the successive dynodes is applied to the successive sections of the vertical deflection plate and the transit time of the beam of the display cathode ray tube section is correlated with the transit time of the electrons from a preceding to a succeeding dynode.

In FIGURE 3 an arrangement generally similar to FIGURE 2 has been shown, the construction being Slightly modified, however, to simplify it and to improve performance by reducing the deflection plate and dynode stray capacity and minimize lead inductance. Thus as shown in FIGURE 3 the subsections 18a, 18b and 18a of the lower deflection plate 18 are made integral with the alternate dynode elements 28, 31 and 33. As in the construction of FIGURE 2 the transit time of the electrons from dynode to dynode is made to correspond to the transit time of the electron beam from a preceding portion of the deflection plate 18 to a succeeding portion thereof, the beam thus being progressively deflected as it passes down the tube axis.

What is claimed is:

1. In a device of the class described, in combination, a cathode ray tube comprising an evacuated envelope having a cylindrical neck portion, and a fluorescent screen at one end of the envelope, said cathode ray tube having an electron gun at the opposite end of the envelope for producing a beam of electrons and deflecting plates arranged to deflect the beam from its axis, a generally tubular branch portion formed integrally with the envelope, a travelling wave amplifier comprising an electron gun, nondispersive travelling wave producing means and a velocity demodulating device arranged in said branch envelope portion, and means applying the output of said travelling wave amplifier to one pair of deflection plates of said cathode ray tube to thereby produce a trace on the fluorescent screen in accordance with an input signal applied to the travelling wave producing means.

2. In a device of the class described, in combination, a cathode ray tube comprising an evacuated envelope having a cylindrical neck portion and a funnel portion, and a fluorescent screen at one end of the funnel portion, said cathode ray tube having an electron gun for producing a beam of electrons at the opposite end of the cylindrical portion and deflecting plates arranged to deflect the beam from its axis, a generally tubular branch portion formed integrally with the envelope, a travelling wave amplifier comprising an electron gun, nondispersive travelling wave producing means and a velocity demodulating device arranged in said branch envelope portion and means applying the output of said travelling wave amplifier directly to one pair of deflection plates of said cathode ray tube to thereby produce a trace on the fluorescent screen in accordance with an input signal applied to the travelling wave producing means.

' 3. In a device of the class described, in combination, a cathode ray tube comprising an evacuated envelope having a cylindrical neck portion and a funnel portion, and a fluorescent screen at one end of the funnel portion, said cathode ray tube having an electron gun for producing a beam of electrons at the opposite end of the cylindrical portion and deflecting plates arranged to deflect the beam from its axis, a generally tubular branch portion formed integrally with the envelope, a travelling wave amplifier comprising an electron gun, nondispersive travelling wave producing means and a velocity demodulating device arranged in said branch envelope portion, an electron multiplier in said envelope, means for applying the velocity modulated electron stream to said electron multiplier and means for applying the amplified signal from said electron multiplier to one pair of deflection plates of said cathode ray tube to thereby produce a trace on the fluorescent screen in accordance with the input signal applied to the travelling wave producing means.

4. In a device of the class described, in combination, an evacuated envelope comprising generally tubular portions and a fluorescent screen in said envelope at one end of the axis of a first one of said tubular portions, a first electron gun at the opposite end of said first tubular portion, deflection means in the first said tubular portion for deflecting the electron beam from said first gun in one dimension across said screen, a second electron gun in the second of said tubular portions, means in said second tubular portion for producing a nondispersive travelling wave of input signal energy to velocity modulate the beam from said second electron gun, means to apply an amplitude modulated signal to said travelling wave producing means, means located in said second tubular portion at a point along said portion remote from said second electron gun to demodulate the beam from said second gun to produce signals corresponding to the input signal, and means to apply said demodulated signals to said deflecting means to thereby produce a trace on said fluorescent screen in accordance with the input signal.

5. A device in accordance with claim wherein said travelling wave producing means comprises a helical line extending along the axis of said second tubular portion adjacent said second electron gun.

6. A device in accordance with claim 4 wherein said demodulating means comprises an apertured plate together with means for applying a potential to said plate to cause said plate to permit only electrons having a velocity above a predetermined minimum to pass through the aperture.

7. A device in accordance with claim 5 wherein said input signal applying means comprises a pair of coupling electrodes located respectively adjacent the ends of said helical line.

8. A device in accordance with claim 5 wherein said demodulating means comprises an apertured plate together with means for applying a potential to said plate to cause said plate to permit only electrons having a velocity above a predetermined minimum to pass through the aperture.

9. In a device of the class described, in combination, an evacuated envelope comprising generally tubular portions and a fluorescent screen in said envelope at one end of the axis of a first one of said tubular portions, a first electron gun at the opposite end of said first tubular portion, deflection means in the first said tubular portion for deflecting the electron beam from said first gun, a second electron gun in the second of said tubular portions, means in said second tubular portion adjacent said second electron gun for producing a travelling wave of input signal energy to velocity modulate the beam from said envelope, said demodulated beam being applied to said electron multiplier means and means for applying the output of said multiplier means to said deflection means to deflect the beam form said first electron gun in accordance with the input signals, to thereby produce the trace on said fluorescent screen in accordance With the input signal.

10. In a device of the class described, in combination, an evacuated envelope comprising generally tubular portions and a fluorescent screen in said envelope at one end of the axis of a first one of said tubular portions, a first electron gun at the opposite end of said first tubular portion, deflection means in the first said tubular portion for deflecting the electron beam from said first gun in one dimension across said screen, said deflection means comprising a plurality of pairs of deflection plates located along the axis of the beam from said first electron gun, a second electron gun in a second tubular portion, means in said second tubular portion for producing a travelling Wave of input signal energy to velocity modulate the beam from said second electron gun, means to apply an amplitude modulated signal to said travelling wave pro ducing means, means located in said second tubular portion adjacent said travelling wave producing means to demodulate the beam from said second gun to produce signals corresponding to the input signal, and electron multiplier means comiprsing a plurality of dynodes located in said evacuated envelope, the first of said dynodes being located in the path of electrons from said demodulating means and successive ones of said dynodes being connected to one plate of successive ones of said pairs of deflection plates to deflect the beam from said first electron gun in accordance with the input signals applied to said travelling Wave producing means.

11. In a device of the class described, in combination, an evacuated envelope comprising generally tubular portions and a fluorescent screen in said envelope at one end of the axis of a first one of said tubular portions, a first electron gun at the opposite end of said first tubular portion, deflection means in the first said tubular portion for deflecting the electron beam from said first gun in one dimension across said screen, said deflection means comprising a plurality of pairs or" deflection plates located along the axis of the beam from said first electron gun, one plate of each pair being on one side of the beam axis and the other plate on the opposite side, said plates on said one side being biased successively more positive in the direction from the gun to the screen, a second electron gun in the second of said tutbular portions, means in said second tubular portion for producing a travelling wave of input signal energy to velocity modulate the beam from said second electron gun, means to apply an amplitude modulated signal to said travelling wave producing means, means located in said second tubular portion adjacent said travelling wave producing means to demodulate the velocity modulated beam from said second gun to produce signals corresponding to the input signal, electron multiplier means comprising a plurality of dynodes in said evacuated envelope, the first of said dynodes being located in the path of the electrons from said demodulated means, successive ones of said dynodes being connected to the other plate of successive ones of said pair of plates, means biasing said dynodes successively more positive to cause electron multiplier action, said biasing means being correlated with said bias on said one plate of said successive pairs of said deflection plates to thereby center the electron beam from said first gun of said screen in the absence of input signals.

12. In a device of the class described, in combination, an evacuated envelope comprising generally tubular portions and a fluorescent screen in an enlarged portion of said envelope at one end of the axis of a first one of said tubular portions, a first electron gun at the opposite end of said first tubular portion, deflection means in the first said tubuluar portion for deflecting the electron beam from said first gun in one dimension across said screen,

said deflection means comprising a plurality of pairs of deflection plates located along the axis of the beam from said first electron gun, said plates of said one side being biased successively more positive in the direction from the gun to the screen, a second electron gun in the second of said tubular portions, means in said second tubular portion for producing a travelling wave of input signal energy to velocity modulate the beam from said second electron gun, means to apply an amplitude modulated signal to said travelling wave producing means, means located in said second tubular portion adjacent said travelling wave producing means to demodulate the velocity modulated beam from said second gun to produce signals corresponding to the input signal, and electron multiplier means comprising a plurality of dynodes in said evacuated envelope, the first of said dynodes being located in the path of electrons from said demodulating means, odd numbered ones of said dynodes starting with the dynode adjacent said demodulating means being made integral with successive ones of said deflection plate pairs to thereby deflect the beam from said first electron gun in accordance with the input signals.

13. In a device of the class described, in combination, an evacuated envelope comprising generally tubular portions and a fluorescent screen in said envelope at one end of the axis of a first one of said tubular portions, a first electron gun at the opposite end of said first tubular portion, deflection means in the first said tubular portion for deflecting the electron beam from said first gun in one dimension across said screen, said deflection means comprising a plurality of pairs of deflection plates located along the axis of the beam from said first electron gun, said plates on said one side being biased successively more positive in the direction from the gun to the screen, a second electron gun in the second of said tubular portions, means in said second tubular portion for producing a travelling wave of input signal energy to velocity modulate the beam from said second electron gun, means to apply an amplitude modulated signal to said travelling wave producing means, means located in said second tubular portion adjacent said travelling Wave producing means to demodulate the velocity modulated beam from said second gun to produce signals corresponding to the input signal, electron multiplier means comprising a plurality of dynodes in said evacuated envelope, the first of said dynodes being located in the path of electrons from said demodulating means, odd numbered ones of said dynodes starting with the dynode adjacent said demodulating means being made integral with successive ones of said deflection plate pairs, means biasing said dynodes successively more positive to cause electron multiplier action, said biasing means being correlated with said bias on said one plate of said successive pairs of said deflection plates to thereby center the electron beam from said first gun of said screen in the absence of input signals, whereby the beam from said first electron gun is deflected from a center position on said fluorescent screen in accordance with input signals.

References Cited by the Examiner UNITED STATES PATENTS 2,181,720 11/39 Barthelemy 3l55.26 2,408,423 10/46 Hartley 3155.11 2,630,544 3/53 Tiley 3153.6 3,035,264 5/62 Fuller et a1. 31539.3 X 3,118,110 1/64 Spangenberg 315-3.5 X

GEORGE N. WESTBY, Primary Examiner.

RALPH G. NILSON, ROBERT SEGAL, Examiners. 

1. IN A DEVICE OF THE CLASS DESCRIBED, IN COMBINATION, A CATHODE RAY TUBE COMPRISING AN EVACUATED ENVELOPE HAVING A CYLINDRICAL NECK PORTION, AND A FLUORESCENT SCREEN AT ONE END OF THE ENVELOPE, SAID CATHODE RAY TUBE HAVING AN ELECTRON GUN AT THE OPPOSITE END OF THE ENVELOPE FOR PRODUCING A BEAM OF ELECTRONS AND DEFLECTING PLATES ARRANGED TO DEFLECT THE BEAM FROM ITS AXIS, A GENERALLY TUBULAR BRANCH PORTION FORMED INTEGRALLY WITH THE ENVELOPE, A TRAVELLING WAVE AMPLIFIER COMPRISING AN ELECTRON GUN, NONDISPERSIVE TRAVELLING WAVE PRODUCING MEANS AND A VELOCITY DEMODULATING DEVICE ARRANGED IN SAID BRANCH ENVELOPE PORTION, AND MEANS APPLYING THE OUTPUT OF SAID TRAVELLING WAVE AMPLIVIER TO ONE PAIR OF DEFLECTION PLATES OF SAID CATHODE SCREEN IN ACCORDANCE WITH AN INPUT SIGNAL APPLIED TO THE TRAVELLING WAVE PRODUCING MEANS. 